[pull] main from python:main

Doc/using/configure.rst

@@ -789,14 +789,15 @@ also be used to improve performance.
 
    - ``-fno-omit-frame-pointer`` and/or ``-mno-omit-leaf-frame-pointer``
      are added when the compiler supports them.
-   - ``-marm`` is added on 32-bit ARM when supported,
+   - ``-marm`` and/or ``-mno-thumb`` is added on 32-bit ARM when supported,
    - on s390x platforms, when supported, ``-mbackchain`` is added *instead*.
      of the above frame pointer flags.
+   - on ppc64le platforms, no compiler flags is needed since the power ABI
+     requires that compilers maintain a back chain by default.
 
    Frame pointers enable profilers, debuggers, and system tracing tools
    (``perf``, ``eBPF``, ``dtrace``, ``gdb``) to walk the C call stack
-   without DWARF metadata.
-   The flags propagate to third-party C
+   without DWARF metadata. The flags propagate to third-party C
    extensions through :mod:`sysconfig`. On compilers that do not
    understand them, the build silently skips them.
 

Lib/test/test_frame_pointer_unwind.py

@@ -56,6 +56,12 @@ def _frame_pointers_expected(machine):
             if sys.maxsize < 2**32:
                 return None
             return True
+        if machine == "ppc64le":
+            # The power ABI specification requires that compilers maintain a
+            # back chain by default, so unwinding already works without a
+            # dedicated frame pointer.
+            # https://openpowerfoundation.org/specifications/64bitelfabi/
+            return True
         if machine == "x86_64":
             final_opt = ""
             for opt in cflags.split():

Modules/_testinternalcapi.c

@@ -92,6 +92,12 @@ static const uintptr_t min_frame_pointer_addr = 0x1000;
 #  define FRAME_POINTER_NEXT_OFFSET 0
 #  define FRAME_POINTER_RETURN_OFFSET \
     (S390X_FRAME_RETURN_ADDRESS_OFFSET / (Py_ssize_t)sizeof(uintptr_t))
+#elif defined(__powerpc64__) || defined(__ppc64__)
+// ppc64le puts the return address at fp[2]; it saves the Condition Register
+// in fp[1]. See:
+// https://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi-1.9.html#STACK
+#  define FRAME_POINTER_NEXT_OFFSET 0
+#  define FRAME_POINTER_RETURN_OFFSET 2
 #else
 #  define FRAME_POINTER_NEXT_OFFSET 0
 #  define FRAME_POINTER_RETURN_OFFSET 1

configure.ac

@@ -2549,9 +2549,16 @@ AS_VAR_IF([ac_cv_gcc_compat], [yes], [
         frame_pointer_cflags="$frame_pointer_cflags -mno-omit-leaf-frame-pointer"
       ], [], [-Werror])
       AS_CASE([$host_cpu], [arm|armv*], [
+        dnl GCC uses "-marm"; clang uses "-mno-thumb"
         AX_CHECK_COMPILE_FLAG([-marm], [
           frame_pointer_cflags="$frame_pointer_cflags -marm"
         ], [], [-Werror])
+        AX_CHECK_COMPILE_FLAG([-mno-thumb], [
+          frame_pointer_cflags="$frame_pointer_cflags -mno-thumb"
+        ], [], [-Werror])
+      ])
+      AS_CASE([$host_cpu], [powerpc64le], [
+        frame_pointer_cflags=""
       ])
       AS_CASE([$host_cpu], [s390*], [
         AX_CHECK_COMPILE_FLAG([-mbackchain], [